Three different areas of work are being pursued with Strongyloides stercoralis. One area involves further evaluation of the ELISA test for serum antibodies to the parasite in patients. This test has already been found to be useful in diagnosis of infection, but is under investigation now primarily to follow the decline in antibody levels after treatment. The ELISA test thus may be useful in diagnosis of active infections, and to confirm cure after treatment. Another direction of study is the preparation and testing of skin test antigens prepared from Strongyloides larvae for evidence of immediate hypersensitivity in patients. The third area of research is the use of the Patas monkey as a model for hyperinfection with the human parasite, S. stercoralis.